This is a great question and one that has many answers. At its most basic definition SharePoint is a web application from Microsoft that enables organizations to work more efficiently by letting users share documents, data and information. There are multiple SharePoint products for organizations to choose from, each offering a unique set of benefits.
Free (Foundation)
SharePoint Foundation is the free product that contains the basic collaboration features which includes lists, document libraries, workflows, calendars, team sites and more.
A list is exactly that, a list, and can have multiple columns much like a workbook in Excel or a table in MS Access or any other database. You can store data as rows and create views to display the data in different ways through filters, sorting and grouping.
A document library is used to store documents and files and functions much like a list in that you may add columns to tag the document and create views. You can also enable versioning of documents as well as have the ability to check out document for editing and checking them back in.
Workflows may be applied to items stored in lists or documents stored in libraries. They can be as simple as notifying a person when the value of a column is updated or as complicated as a process that involves dozens or even hundreds of steps and tasks.
Calendars are used to keep track of meetings, appointments and events. It’s basically a type of list and you may add extra columns, create views and apply workflows. You may also connect Outlook calendars and overlay (stack) SharePoint calendars on top of one another.
A team site is a web site that you can create for a single document, meeting, process, department, organization or anything else you can think of. The point is you can store all data and information related to a single subject, entity or process within a site. Lists, document libraries, calendars, workflows and web pages are stored within a site.
Paid (Server)
SharePoint Server 2013 is the advanced product that you may license for a cost and includes all the features of Foundation as well as social computing, enterprise search, web content management, business intelligence, business connectivity and electronic forms just to name a few.
Social Computing in SharePoint 2013 includes the ability for users to tag, rate and bookmark content. Hashtags are a newly introduced social tagging feature and if you’re a Twitter user you’ll know what they are. Social networking is possible through My Sites and user profiles. Finally, new to SharePoint 2013 is the Community Site. Community sites act as forums for users to communicate through discussions on topics.
Enterprise search allows different sources of content to be indexed and searchable through SharePoint. You may index SharePoint sites, external web sites, file shares and other types of repositories and systems. The search component is now a part of the SharePoint engine itself and is used to power many components within SharePoint 2013.
Web content management enables organizations to publish 100% custom branded web sites through structured templates. Content can be maintained at the editorial level instead of having to go through IT. SharePoint 2013 also supports multilingual web sites.
Business intelligence solutions can be implemented through a variety of services the are packaged with SharePoint 2013 Server. Dashboards of information and data can be created through knowledge performance indicators, views and reports, MS Excel workbooks and MS Access components. Some of the services used to create the BI components include SQL Reporting services, Excel services and MS Access services.
Electronic forms can be developed using Microsoft InfoPath and hosted within the browser using Forms services. The data can be saved as xml files or directly within a SharePoint list. Infopath enables users to create forms without the need of a programmer.
Online (Office365)
More and more, organizations are moving to the “cloud” to host their solutions and Microsoft offers Office365 which includes Office, Exchange/Outlook and SharePoint. The cloud is an abstract term for servers maintained by companies, that provide such services, for customers to be able to host their systems and applications for a monthly fee, usually per user. The benefits for customers include not having to worry about maintaining their own systems and applications as well as disaster recovery.
The cloud version of SharePoint offers everything listed above. There are some limitations when it comes to developing custom solutions as there are limits to what one can do on the server side but SharePoint 2013 provides developers with new options for developing with client-side technologies that, for the most part, offset the limitations.
For Developers
SharePoint is a .NET platform that developers can use to build applications and take advantage of it’s features. For example, lists in SharePoint now support the capabilities of relational databases. Advanced data models can be built and relationships between lists established through lookup columns much in the same way as foreign keys in database tables. This means that joins are now possible through LINQ or collaborative application markup language (CAML).
Other things developers can take advantage of when using SharePoint is it’s document management capabilities, security system and workflow engine.
Conclusion
As you can see SharePoint is a very large platform that can help organizations in many areas. It’s important to have a general understanding of the different products and all the major features in order to use SharePoint more effectively. Hopefully this article has provided a good first step on your understanding of SharePoint. The best online resource I’ve found so far is lynda.com. To date, there are 322 courses and videos that cover almost every aspect of SharePoint. If you can’t find the answer to your questions there you can always contact me and I’ll be happy to answer as best as I can.